Alloy compositions

ABSTRACT

The present disclosure provides compositions comprising iron, about 0.01 to about 0.4% w/w of manganese; about 1.3 to about 1.9% w/w of chromium; about 0.10% w/w or less of nickel; about 1.2 to about 1.7% w/w of molybdenum; about 0.01 to about 0.4% w/w of niobium; about 0.01 to about 0.4% w/w of vanadium; about 1.5 to about 2% w/w of silicon; and about 0.01 to about 0.20% w/w of carbon. The present disclosure also provides methods of preparing a metal powder, comprising atomizing a composition described herein and methods of preparing a metal object, comprising subjecting metal powder described herein to metal binder jetting.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of the priority of U.S. ProvisionalPatent Application No. 63/255,670, filed Oct. 14, 2021, the disclosureof which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

This disclosure provides novel alloy compositions and methods for usingthese compositions.

BACKGROUND

As with many metal processing techniques, powder metallurgy processeshave evolved over the years with technologies such as warm compaction,injection molding, sinter-hardening, high temperature sintering,bonding, powder forging and green machining. Recently, additivemanufacturing has been the latest technology to seek acceptance as astandard powder metallurgy process. While there are many types ofadditive manufacturing processes that can be classified either by thenature of the feedstock utilized (powder or wire) and/or the method bywhich the parts are fabricated (laser melted or glued by binder in thecase of powders), one common theme is that the alloy composition (in thecase of metals) and the processing must be considered together toproduce a high performing finished product.

As with most additive manufacturing processes, metal binder jettinginvolves the deposition of powder layer by layer, with each layer andpowder particle held together by a polymeric glue. The glue or binder isapplied to the powder bed utilizing a print head very similar to thoseutilized by ink jet printing. Then, like conventional powder metallurgyprocesses, the part needs to be sintered to its final shape and density.Compared with the competing additive manufacturing technology, laserpowder bed fusion, where the powder layers are melted together with theuse of a laser, metal binder jetting lags in industrialization. However,with new and advanced machine technology being introduced, thethroughput of the metal binder jetting has shown significant improvementand now the technology is targeting serial production of industrialparts. In addition, metal binder jetting is not limited to alloys whichare weldable but can be utilize a wider range of materials. To achievehigh densities (>98%), fine powders are used with a mean particle, d₅₀size ranging from 10-15 μm. Utilizing fine powders results in a superiorsurface quality, about 20% better than laser powder bed fusion.

The automotive industry is evaluating the use of metal binder jettingfor producing automotive parts. In particular, because of the ability of3D printing to produce designs that are conducive to weight reductions,a particular interest by the automotive makers is the application ofsheet material for body and chassis parts. These steels used for theseapplications are generally classified as advanced high strength steels.

Advanced high strength steels or micro alloyed steels generally givesuperior mechanical properties utilizing low alloy levels of alloycontent coupled with thermo-mechanical processing (typically rolling incombination with accelerated cooling). Dual-phase (DP) steels areconsidered a subclass of advanced high strength steels and exhibit amicrostructure consisting of a hard phase (primarily martensite and/orbainite) in a matrix of ferrite. Due to their composite microstructures,dual phase steels exhibit excellent mechanical properties with tensilestrength generally dependent primarily on the volume fraction ofmartensite. Dual phase steels typically contain ˜20% martensite grainsthat induce significant work hardening of ferrite and therefore, highultimate tensile strengths. The high percentage of ferrite leads to highductility with homogeneous plastic flow that eliminates the Luders bandsand hence eliminates the wrinkling or stretcher marks and allows for amore aesthetically pleasing surface. Dual phase steels also benefit fromthe fact that their low carbon content makes them more weldable thansteels of comparable strength, allowing their use in automotive exteriorskin panels and structural reinforcements.

The manufacture of these sizable products normally requires considerablecapital investment in stamping equipment and expensive tooling. Forprototyping and limited run production, additive manufacturing can be avaluable tool to produce a multitude of designs without the need forexpensive tooling and equipment.

Thus, there is a need in the art for alloy compositions for use inadditive manufacturing.

SUMMARY

The present disclosure provides compositions comprising iron, about 0.01to about 0.4% w/w of manganese; about 1.3 to about 1.9% w/w of chromium;about 0.1% w/w or less of nickel; about 1.2 to about 1.7% w/w ofmolybdenum; about 0.01 to about 0.4% w/w of niobium; about 0.01 to about0.4% w/w of vanadium; about 1.5 to about 2% w/w of silicon; and about0.01 to about 0.20% w/w of carbon.

The present disclosure also provides methods of preparing a metalpowder, comprising atomizing a composition described herein.

The present disclosure further provides methods of preparing a metalobject, comprising subjecting metal powder described herein to metalbinder jetting.

BRIEF DESCRIPTION OF THE DRAWINGS

The present application is further understood when read in conjunctionwith the appended drawings. For the purpose of illustrating the subjectmatter, there are shown in the drawings exemplary embodiments of thesubject matter; however, the presently disclosed subject matter is notlimited to the specific compositions and methods disclosed. In addition,the drawings are not necessarily drawn to scale.

FIG. 1 is a dot plot of sintered density versus as built density as afunction of mean particle size (d₅₀) for 316 L gas atomized stainlesssteel powder sintered at 1260° C. in 100% hydrogen.

FIG. 2 are phase diagrams for (left) DP600 and new alloy FSLA (right).

FIG. 3 is a plot of measured values of ferrite versus calculated levelsas a function of the intercritical anneal temperature of the FSLA alloy.

FIG. 4 is CCT diagram for FSLA Alloy highlighting cooling rates thattransform the structure to bainite or martensite (intercritical annealtemperature 865° C., starting grain size 100 microns).

FIGS. 5A and 5B are photographs showing the microstructure of FSLA alloyinter-critically annealed at 843° C. and cooled at a rate of 1.3°C./sec. FIG. 5A is a photograph showing the general microstructure. FIG.5B is a photograph at a higher magnification identifying the bainite aswell as the two type of ferrite dislocated (dark) and non-dislocated.

FIG. 6 are photographs showing electron backscattered diffraction ofFSLA intercritically annealed at 850° C. and cooled at 1.3° C./sec.

FIGS. 7A and 7B are SEM micrographs and corresponding EDS ofprecipitates. FIG. 7A is a micrograph/EDS of niobium carbide particles.FIG. 7B is a micrograph/EDS for molybdenum carbide particles.

FIG. 8 is a bar graph showing average precipitate diameter in micronsand area fraction of precipitates in two FSLA samples afterintercritically annealing.

FIG. 9 is a line graph showing the comparison of FSLA with wroughtversions of dual phase steels.

FIG. 10 is a bar graph showing the calculation of strength contribution.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

In the present disclosure the singular forms “a”, “an” and “the” includethe plural reference, and reference to a particular numerical valueincludes at least that particular value, unless the context clearlyindicates otherwise. Thus, for example, a reference to “a material” is areference to at least one of such materials and equivalents thereofknown to those skilled in the art, and so forth.

When a value is expressed as an approximation by use of the descriptor“about” it will be understood that the particular value forms anotherembodiment. In general, use of the term “about” indicates approximationsthat can vary depending on the desired properties sought to be obtainedby the disclosed subject matter and is to be interpreted in the specificcontext in which it is used, based on its function. Where present, allranges are inclusive and combinable. That is, references to valuesstated in ranges include every value within that range.

It is to be appreciated that certain features of the invention whichare, for clarity, described herein in the context of separateembodiments, may also be provided in combination in a single embodiment.That is, unless obviously incompatible or excluded, each individualembodiment is deemed to be combinable with any other embodiment(s) andsuch a combination is considered to be another embodiment. Conversely,various features of the invention that are, for brevity, described inthe context of a single embodiment, may also be provided separately orin any sub-combination. It is further noted that the claims may bedrafted to exclude any optional element. As such, this statement isintended to serve as antecedent basis for use of such exclusiveterminology as “solely,” “only” and the like in connection with therecitation of claim elements, or use of a “negative” limitation.Finally, while an embodiment may be described as part of a series ofsteps or part of a more general structure, each said step may also beconsidered an independent embodiment in itself.

As described herein, the disclosure provides metal compositions andmetal powders that provide dual phase-low alloy steels. These steelsexhibit enhanced diffusion at the sintering temperature leading to highdensities. The alloy constituents are formulated, so that upon coolingfrom the sintering temperature, the transformation products allow thealloy to reach the desired mechanical properties. In particular, themicrostructure of the alloy can be varied post-sintering, by heattreatment (i.e., different inter-critical annealing temperatures), togive a wide range of mechanical properties. For example, the metalcompositions or metal powders are useful in metal binder jet technologyto meet a targeted set of properties with the end goal to reach theperformance of a competing technology (metal stamping) for an automotiveapplication. Thus, the metal compositions exhibit a high degree ofsinterability when compared to other low alloy steels used for metalbinder jetting. Further, once sintered, the metal compositions providemetal parts with slightly lower ductility. By using metal binderjetting, it is possible to serially produce cost sensitive parts muchfaster than other additive manufacturing technologies, e.g., laserpowder bed fusion.

Metal Compositions

The disclosure provides compositions comprising iron and additionalcomponents including manganese, chromium, nickel, molybdenum, niobium,vanadium, silicon, and carbon. Because iron forms the basis and majorcomponent of these compositions, these are “iron-based compositions. Insome embodiments, the iron is the base element. The base-iron can be inthe form of a powder or particles of pure iron, substantially pure iron,or iron pre-alloyed with at least one alloying element. In theiron-based powder compositions disclosed herein, the particles of ironor pre-alloyed iron are in combination with powders of the otheralloying elements to provide a final metal composition.

“Pure iron” (or “pure iron particles”) as used herein refers to ironcontaining no more than about 0.01% w/w of normal impurities. In orderto provide the required iron content, elemental iron may be added to themetal compositions. In some embodiments, about 2 to about 7% w/w, basedon the total weight of the composition, of elemental iron may be added.In other embodiments, about 2, about 2.5, about 3, about 3.5, about 4,about 4.5, about 5, about 5.5, about 6, about 6.5, or about 7, based onthe total weight of the composition, of elemental iron may be added. Infurther embodiments, about 2 to about 6.5, about 2 to about 6, about 2to about 5.5, about 2 to about 5, about 2 to about 4.5, about 2 to about4, about 2 to about 3.5, about 2 to about 3, about 2 to about 2.5, about2.5 to about 7, about 2.5 to about 6.5 m about 2.5 to about 6, about 2.5to about 5.5, about 2.5 to about 5, about 2.5 to about 4.5, about 2.5 toabout 4, about 2.5 to about 3.5, about 2.5 to about 3, about 3 to about7, about 3 to about 6.5, about 3 to about 6, about 3 to about 5.5, about3 to about 5, about 3 to about 4.5, about 3 to about 4, about 3 to about3.5, about 3.5 to about 7, about 3.5 to about 6.5, about 3.5 to about 6,about 3.5 to about 5.5, about 3.5 to about 5, about 3.5 to about 4.5,about 3.5 to about 4, about 4 to about 7, about 4 to about 6.5, about 4to about 6, about 4 to about 5.5, about 4 to about 5, about 4 to about4.5, about 4.5 to about 7, about 4.5 to about 6.5, about 4.5 to about 6,about 4.5 to about 5.5, about 4.5 to about 5, about 5 to about 7, about5 to about 6.5, about 5 to about 6, about 5 to about 5.5, about 5.5 toabout 7, about 5.5 to about 6.5, about 6 to about 6, about 6 to about6.5, or about 6.5 to 7% w/w, based on the total weight of thecomposition, of elemental iron may be added. In yet other embodiments,about 3 to about 5% w/w, based on the total weight of the composition,of elemental iron may be added.

“Substantially pure iron” (or “substantially pure iron particles”) asused herein refers to iron containing no more than about 1.0% w/w, basedon the total weight of the composition, preferably no more than about0.5% w/w of normal impurities. Examples of substantially pure ironinclude highly compressible, metallurgical-grade iron powders. Specificexamples of substantially pure iron powders include the ANCORSTEEL® 1000series of pure iron powders, such as the following:

-   -   A composition comprising iron and less than about 0.01% w/w        carbon, less about 0.14% w/w oxygen, about 0.002% w/w nitrogen,        about 0.018% w/w sulfur, about 0.009% w/w phosphorus, less than        about 0.01% w/w silicon, about 0.2% w/w manganese, about 0.07%        w/w chromium, about 0.10% w/w copper, and about 0.08% w/w nickel        (also known as ANCORSTEEL® 1000);    -   A composition comprising iron and less than about 0.01% w/w        carbon, about 0.09% w/w oxygen, about 0.001% w/w nickel, about        0.009% w/w sulfur, about 0.005% w/w phosphorus, less than about        0.01% w/w silicon, about 0.10% w/w manganese, about 0.03% w/w        chromium, about 0.05% w/w copper, and about 0.05% w/w nickel        (also known as ANCORSTEEL® 1000B),    -   A composition comprising iron and less than about 0.01% w/w        carbon, about 0.07% w/w oxygen, about 0.001% w/w nitrogen, about        0.007% w/w sulfur, about 0.004% w/w phosphorus, less than about        0.01% w/w silicon, about 0.07% w/w manganese, about 0.02% w/w        chromium, about 0.03% w/w copper, and about 0.04% w/w nickel        (also known as ANCORSTEEL® 1000 C),    -   A composition comprising iron and about 0.01% w/w carbon, about        0.02% w/w silicon, about 0.15% w/w oxygen, and about 0.015% w/w        sulfur (also known as ANCORSTEEL® AMH), or    -   A composition comprising iron and about 0.01% w/w carbon, about        0.02% w/w silicon, about 0.15% w/w oxygen, and about 0.015% w/w        sulfur (also known as ANCORSTEEL® DWP200)

Other substantially pure iron powders that can be used herein includesponge iron powders, such as a composition comprising iron and about0.02% w/w silicon dioxide, about 0.01% w/w carbon, about 0.009% w/wsulfur, and about 0.01% w/w phosphorus (also known as ANCOR MH-100powder).

The ANCORSTEEL® low alloy steel powders are substantially pure iron andcontain a low level of alloy components. Such low alloy steel powdersinclude, without limitation, the following:

-   -   A composition comprising iron and less than about 0.01% w/w        carbon, about 0.35% w/w molybdenum, about 0.15% w/w manganese,        and about 0.13% w/w oxygen (also known as ANCORSTEEL® 30HP),    -   A composition comprising iron and less than about 0.01% w/w        carbon, about 0.18% w/w manganese, about 0.50% w/w molybdenum,        about 0.09% w/w oxygen (also known as ANCORSTEEL® 50 HP),    -   A composition comprising iron and less than about 0.01% w/w        carbon, about 0.12% w/w manganese, about 0.86% w/w of        molybdenum, and about 0.08% w/w oxygen (also known as        ANCORSTEEL® 85 HP),    -   A composition comprising iron and less than about 0.01% w/w        carbon, about 0.12% w/w manganese, about 1.5% w/w molybdenum,        and about 0.08% w/w oxygen (also known as ANCORSTEEL® 150 HP),

Overall, regardless of the source of the iron, the compositions containan amount of iron that results in an 100% w/w based on the % w/w of theother components of the composition. In other words, the amount of theiron and other components of the composition adds up to 100% w/w. Insome embodiments, the compositions contain about 85 to about 96% w/w ofiron. In other embodiments, the compositions contain about 85, about 86,about 87, about 88, about 89, about 90, about 91, about 92, about 93,about 94, about 95, or about 96% w/w of iron. In further embodiments,the compositions contain about 85 to about 96, about 85 to about 95,about 85 to about 94, about 85 to about 93, about 85 to about 92, about85 to about 91, about 85 to about 90, about 85 to about 89, about 85 toabout 88, about 85 to about 87, about 85 to about 86, about 86 to about96, about 86 to about 95, about 86, about 94, about 86 to about 93,about 86 to about 92, about 86 to about 91, about 86 to about 90, about86 to about 89, about 86 to about 88, about 86 to about 87, about 87 toabout 96, about 87 to about 95, about 87 to about 94, about 87 to about93, about 87 to about 92, about 87 to about 91, about 87 to about 90,about 87 to about 89, about 87 to about 88, about 88 to about 96, about88 to about 95, about 88 to about 94, about 88 to about 93, about 88 toabout 92, about 88 to about 91, about 88 to about 90, about 88 to about89, about 89 to about 96, about 89 to about 95, about 89 to about 94 mabout 89 to about 93, about 89 to about 92, about 89 to about 91, about89 to about 90, about 90 to about 96, about 90 to about 95, about 90 toabout 94, about 90 to about 93, about 90 to about 92, about 90 to about91, about 91 to about 96, about 91 to about 95, about 91 to about 94,about 91 to about 93, about 91 to about 92, about 92 to about 96, about92 to about 95, about 92 to about 94, about 92 to about 93, about 93 toabout 96, about 93 to about 95, about 93 to about 94, about 94 to about96, about 94 to about 95, or about 95 to about 96% w/w of iron. Infurther embodiments, the compounds contain about 94 to about 96% w/w ofiron. In yet other embodiments, the compositions contain about 94.1 toabout 95.4% w/w of iron. In still further embodiments, the compositionscontain about 94.11 to about 95.44% w/w of iron.

As previously noted, the compositions contain additional components.These components are balanced in the composition so as to provide a dualphase microstructure. In some embodiments, the elements which formaustenite (e.g., carbon, copper, nickel) are balanced with those thatform ferrite (e.g., chromium, molybdenum, silicon, etc.) in an alloy toform a dual phase microstructure. In addition to aiding in forming thedesired microstructure, the additional elements contribute to formedtransformation products (e.g., bainite and martensite) when the alloy iscooled. These transformation products lead to an increase in the workhardening rate and a sintered metal product having a high strength(e.g., high ultimate tensile strength) and high ductility.

In some embodiments, the compositions comprise about 0.01 to about 0.4%w/w of manganese. In certain aspects, the compositions comprise about0.01, about 0.01, about 0.02, about 0.03, about 0.04, about 0.05, about0.06, about 0.07, about 0.08, about 0.09, about 0.1, about 0.11, about0.12, about 0.13, about 0.14, about 0.15, about 0.16, about 0.17, about0.18, about 0.19, about 0.20, about 0.21, about 0.22, about 0.23, about0.24, about 0.25, about 0.26, about 0.27, about 0.28, about 0.29, about0.30, about 0.31, about 0.32, about 0.33, about 0.34, about 0.35, about0.36, about 0.37, about 0.38, about 0.39, or about 0.4% w/w ofmanganese. In other aspects, the compositions contain about 0.1 to about0.35, about 0.1 to about 0.3, about 0.1 to about 0.25, about 0.1 toabout 0.2, about 0.1 to about 0.15, about 0.25 to about 0.4, about 0.25to about 0.35, about 0.25 to about 0.3, or about 0.3 to about 0.4% w/wof manganese. In further aspects, the compositions contain about 0.1 toabout 0.3% w/w of manganese. In other aspects, the compositions containabout 0.15 to about 0.25% w/w of manganese. In still further aspects,the compositions contain about 0.2% w/w of manganese.

In other embodiments, the compositions contain about 1.3 to about 1.9%w/w of chromium. In certain aspects, the compositions contain about 1.3,about 1.4, about 1.5, about 1.6, about 1.7, about 1.8, or about 1.9% w/wof chromium. In other aspects, the compositions contain about 1.3 toabout 1.8, about 1.3 to about 1.7, about 1.3 to about 1.6, about 1.3 toabout 1.5, about 1.3 to about 1.4, about 1.4 to about 1.9, about 1.4 toabout 1.8, about 1.4 to about 1.7, about 1.4 to about 1.6, about 1.4 toabout 1.5, about 1.5 to about 1.9, about 1.5 to about 1.8, about 1.5 toabout 1.7, about 1.5 to about 1.6, about 1.6 to about 1.9, about 1.6 toabout 1.8, about 1.6 to about 1.7, about 1.7 to about 1.9, about 1.7 toabout 1.8, or about 1.8 to about 1.9% w/w of chromium. In other aspects,the compositions contain about 1.4 to about 1.8% w/w of chromium. Infurther aspects, the compositions contain about 1.5 to about 1.7% w/w ofchromium. In still other aspects, the compositions contain about 1.55 toabout 1.65% w/w of chromium. In yet further aspects, the compositionscontain about 1.6% w/w of chromium.

In further embodiments, the compositions lack nickel, i.e., contain 0%w/w of nickel. In doing so, the compositions have fewer health andsafety concerns.

The compositions may alternatively contain nickel. In yet otherembodiments, the compositions contain about 0.1% w/w or less of nickel.Thus, in certain aspects, the compositions contain about 0.09, about0.08, about 0.07, about 0.06, about 0.05, about 0.04, about 0.03, about0.02, or about 0.01% w/w or less of nickel.

In still further embodiments, the compositions contain about 0.04 toabout 0.1% of nickel. In certain aspects, the compositions contain about0.04, about 0.05, about 0.06, about 0.07, about 0.08, about 0.09, orabout 0.1% w/w of nickel. In other aspects, the compositions containabout 0.04 to about 0.1, about 0.04 to about 0.09, about 0.04 to about0.08, about 0.04 to about 0.07, about 0.04 to about 0.06, about 0.04 toabout 0.05, about 0.05 to about 0.1, about 0.05 to about 0.09, about0.05 to about 0.08, about 0.05 to about 0.07, about 0.05 to about 0.06,about 0.06 to about 0.1, about 0.06 to about 0.09, about 0.06 to about0.08, about 0.06 to about 0.07, about 0.07 to about 0.1, about 0.07 toabout 0.09, about 0.07 to about 0.08, about 0.08 to about 0.1, about0.08 to about 0.09, or about 0.09 to about 0.1% w/w of nickel. Infurther aspects, the compositions contain about 0.05 to about 0.07% w/wof nickel. In still other aspects, the compositions contain about 0.05%w/w of nickel. In yet further aspects, the compositions contain about0.1% w/w of nickel.

The compositions also contain molybdenum. Among other reasons, themolybdenum rich carbides that are formed provide additionalstrengthening while limiting grain growth during heat treatment. Inother embodiments, the compositions contain about 1.2 to about 1.7% w/wof molybdenum. In certain aspects, the compositions contain about 1.2,about 1.3, about 1.4, about 1.5, about 1.6, or about 1.7% w/w ofmolybdenum. In other aspects, the compositions contain about 1.2 toabout 1.7, about 1.2 to about 1.6, about 1.2 to about 1.5, about 1.2 toabout 1.4, about 1.2 to about 1.3, about 1.3 to about 1.7, about 1.3 toabout 1.6, about 1.3 to about 1.5, about 1.3 to about 1.4, about 1.4 toabout 1.7, about 1.4 to about 1.6, about 1.4 to about 1.5, about 1.5 toabout 1.7, about 1.5 to about 1.6, or about 1.6 to about 1.7% w/w ofmolybdenum. In further aspects, the compositions contain about 1.3 toabout 1.6% w/w of molybdenum. In yet other aspects, the compositionscontain about 1.4 to about 1.5% w/w of molybdenum. In still furtheraspects, the compositions contain about 1.45% w/w of molybdenum. Inother aspects, the compositions contains about 1.5% w/w of molybdenum.

The compositions further contain niobium. Among other reasons, theniobium adds to providing the two-phases of austenite and ferrite,thereby permitting higher carbon levels to be utilized. Further, theniobium rich carbides that are formed provide additional strengtheningwhile limiting grain growth during heat treatment. In some embodiments,the compositions comprise about 0.01 to about 0.4% w/w of niobium. Incertain aspects, the compositions comprise about 0.01, about 0.01, about0.02, about 0.03, about 0.04, about 0.05, about 0.06, about 0.07, about0.08, about 0.09, about 0.1, about 0.11, about 0.12, about 0.13, about0.14, about 0.15, about 0.16, about 0.17, about 0.18, about 0.19, about0.20, about 0.21, about 0.22, about 0.23, about 0.24, about 0.25, about0.26, about 0.27, about 0.28, about 0.29, about 0.30, about 0.31, about0.32, about 0.33, about 0.34, about 0.35, about 0.36, about 0.37, about0.38, about 0.39, or about 0.4% w/w of niobium. In other aspects, thecompositions contain about 0.1 to about 0.35, about 0.1 to about 0.3,about 0.1 to about 0.25, about 0.1 to about 0.2, about 0.1 to about0.15, about 0.25 to about 0.4, about 0.25 to about 0.35, about 0.25 toabout 0.3, or about 0.3 to about 0.4% w/w of niobium. In furtheraspects, the compositions contain about 0.1 to about 0.3% w/w ofniobium. In other aspects, the compositions contain about 0.15 to about0.2% w/w of niobium. In still further aspects, the compositions containabout 0.18% w/w of niobium.

The compositions also contain vanadium. Among other reasons, thevanadium, alone or in combination with the niobium, adds to providingthe two-phases of austenite and ferrite, thereby permitting highercarbon levels to be utilized. Further, the vanadium rich carbides thatare formed provide additional strengthening. In some embodiments, thecompositions comprise about 0.01 to about 0.4% w/w of vanadium. Incertain aspects, the compositions comprise about 0.01, about 0.01, about0.02, about 0.03, about 0.04, about 0.05, about 0.06, about 0.07, about0.08, about 0.09, about 0.1, about 0.11, about 0.12, about 0.13, about0.14, about 0.15, about 0.16, about 0.17, about 0.18, about 0.19, about0.20, about 0.21, about 0.22, about 0.23, about 0.24, about 0.25, about0.26, about 0.27, about 0.28, about 0.29, about 0.30, about 0.31, about0.32, about 0.33, about 0.34, about 0.35, about 0.36, about 0.37, about0.38, about 0.39, or about 0.4% w/w of vanadium. In other aspects, thecompositions contain about 0.1 to about 0.35, about 0.1 to about 0.3,about 0.1 to about 0.25, about 0.1 to about 0.2, about 0.1 to about0.15, about 0.25 to about 0.4, about 0.25 to about 0.35, about 0.25 toabout 0.3, or about 0.3 to about 0.4% w/w of vanadium. In furtheraspects, the compositions contain about 0.1 to about 0.3% w/w ofvanadium. In other aspects, the compositions contain about 0.15 to about0.2% w/w of vanadium. In still further aspects, the compositions containabout 0.18% w/w of vanadium.

The compositions further contain silicon. In some embodiments, thecompositions contain about 1.5 to about 2% w/w of silicon. In certainaspects, the compositions contain about 1.5 to about 2, about 1.5 toabout 1.9, about 1.5 to about 1.8, about 1.5 to about 1.7, about 1.5 toabout 1.6, about 1.6 to about 2, about 1.6 to about 1.9, about 1.6 toabout 1.8, about 1.6 to about 1.7, about 1.7 to about 2, about 1.7 toabout 1.9, about 1.7 to about 1.8, about 1.8 to about 2, about 1.8 toabout 1.9, or about 1.9 to about 2% w/w of silicon. In other aspects,the compositions contain about 1.5 to about 1.8% w/w of silicon. Infurther aspects, the compositions contain about 1.5 to about 1.7% w/w ofsilicon In yet other aspects, the compositions contain about 1.6 toabout 1.7% w/w of silicon. In still further aspects, the compositionscontain about 1.6% w/w of silicon.

The compositions of the disclosure also contain carbon. Given the lowamounts of carbon, the metal compositions are more conducive to welding.In some embodiments, the compositions contain about 0.01 to about 0.20%w/w of carbon. In certain aspects, the compositions contain about 0.01,0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, about 0.12,about 0.13, about 0.14, about 0.15, about 0.16, about 0.17, about 0.18,about 0.19, or about 0.2% w/w of carbon. In other aspects, thecompositions contain about 0.05 to about 0.14% w/w of carbon. In furtheraspects, the compositions contain about 0.1 to about 0.14% w/w ofcarbon. In still other aspects, the compositions contain about 0.14% w/wof carbon. In yet further aspects, the compositions contain less thanabout 0.16 w/w of carbon.

The compositions of the disclosure optionally contain additionalcomponents, such as sulfur, oxygen, or nitrogen, or combinationsthereof. Such components typically are present in the iron powder thatis incorporated into the compositions of the disclosure. In one example,the compositions contain sulfur. In some embodiments, the compositionscontain about 0.001 to about 0.015% w/w of sulfur. In certain aspects,the compositions contain about 0.001, about 0.002, about 0.003, about0.004, about 0.005, about 0.006, about 0.007, about 0.008, about 0.009,about 0.01, about 0.011, about 0.012, about 0.013, about 0.014, or about0.015% w/w of sulfur. In other aspects, the compositions contain about0.001 to about 0.015, about 0.001 to about 0.014, about 0.001 to about0.013, about 0.001 to about 0.012, about 0.001 to about 0.011, about0.001 to about 0.01, about 0.001 to about 0.009, about 0.001 to about0.008, about 0.001 to about 0.007, about 0.001 to about 0.006, about0.001 to about 0.005, about 0.001 to about 0.004, about 0.001 to about0.003, about 0.001 to about 0.002, about 0.0025 to about 0.015, about0.0025 to about 0.014, about 0.0025 to about 0.013, about 0.0025 toabout 0.012, about 0.0025 to about 0.011, about 0.0025 to about 0.01,about 0.0025 to about 0.009, about 0.0025 to about 0.008, about 0.0025to about 0.007, about 0.0025 to about 0.006, about 0.0025 to about0.005, about 0.0025 to about 0.004, about 0.0025 to about 0.003, about0.005 to about 0.015, about 0.005 to about 0.014, about 0.005 to about0.013, about 0.005 to about 0.012, about 0.005 to about 0.011, about0.005 to about 0.01, about 0.005 to about 0.009, about 0.005 to about0.008, about 0.005 to about 0.007, about 0.005 to about 0.006, about0.0075 to about 0.005, about 0.0075 to about 0.004, about 0.0075 toabout 0.015, about 0.0075 to about 0.014, about 0.0075 to about 0.013,about 0.0075 to about 0.012, about 0.0075 to about 0.011, about 0.0075to about 0.01, about 0.01 to about 0.015, about 0.01 to about 0.014,about 0.01 to about 0.013, about 0.01 to about 0.012, about 0.01 toabout 0.011, about 0.0125 to about 0.015, about 0.0125 to about 0.014,or about 0.0125 to about 0.013% w/w of sulfur. In further aspects, thecompositions contain about 0.005 to about 0.01% w/w of sulfur. In yetother aspects, the compositions contain about 0.006 to about 0.008% w/wof sulfur. In still further aspects, the compositions contain about0.007% w/w of sulfur.

In another example, the compositions of the disclosure contain oxygen.In some embodiments, the compositions contain about 0.01 to about 0.1%w/w of oxygen. In certain aspects, the compositions contain about 0.01,about 0.02, about 0.03, about 0.04, about 0.05, about 0.06, about 0.07,about 0.08, about 0.09, or about 0.1% w/w of oxygen. In other aspects,the compositions contain about 0.01 to about 0.09, about 0.01 to about0.08, about 0.01 to about 0.07, about 0.01 to about 0.06, about 0.01 toabout 0.05, about 0.01 to about 0.04, about 0.01 to about 0.03, about0.01 to about 0.02, about 0.02 to about 0.1, about 0.02 to about 0.09,about 0.02 to about 0.08, about 0.02 to about 0.07, about 0.02 to about0.06, about 0.02 to about 0.05, about 0.02 to about 0.04, about 0.02 toabout 0.03, about 0.03 to about 0.1, about 0.03 to about 0.09, about0.03 to about 0.08, about 0.03 to about 0.07, k about 0.03 to about0.06, about 0.03 to about 0.05, about 0.03 to about 0.04, about 0.04 toabout 0.1, about 0.04 to about 0.09, about 0.04 to about 0.08, about0.04 to about 0.07, about 0.04 to about 0.06, about 0.04 to about 0.05,about 0.05 to about 0.1, about 0.05 to about 0.09, about 0.05 to about0.08, about 0.05 to about 0.07, about 0.05 to about 0.06, about 0.06 toabout 0.1, about 0.06 to about 0.09, about 0.06 to about 0.08, about0.06 to about 0.07, about 0.07 to about 0.1, about 0.07 to about 0.09,about 0.07 to about 0.08, about 0.08 to about 0.1, about 0.08 to about0.09, or about 0.09 to about 0.1% w/w of oxygen. In further aspects, thecompositions contain about 0.04 to about 0.08% w/w of oxygen. In yetother aspects, the compositions contain about 0.05 to about 0.07% w/w ofoxygen. In still further aspects, the compositions contain about 0.06%w/w of sulfur.

In a further example, the compositions contain about 0.01 to about 0.02%of nitrogen. In certain aspects, the compositions contain about 0.011,about 0.012, about 0.013, about 0.014, about 0.015, about 0.016, about0.017, about 0.018, about 0.019, or about 0.2% w/w of nitrogen. In someaspects, the compositions contain about 0.011 to about 0.019, about0.011 to about 0.018, about 0.011 to about 0.017, about 0.011 to about0.016, about 0.011 to about 0.015, about 0.011 to about 0.014, about0.011 to about 0.013, about 0.011 to about 0.012, about 0.012 to about0.02, about 0.012 to about 0.019, about 0.012 to about 0.018, about0.012 to about 0.017, about 0.012 to about 0.016, about 0.012 to about0.015, about 0.012 to about 0.014, about 0.012 to about 0.013, about0.013 to about 0.02, about 0.013 to about 0.019, about 0.013 to about0.018, about 0.013 to about 0.017, about 0.013 to about 0.016, about0.013 to about 0.015, about 0.013 to about 0.014, about 0.014 to about0.02, about 0.014 to about 0.019, about 0.014 to about 0.018, about0.014 to about 0.017, about 0.014 to about 0.016, about 0.014 to about0.015, about 0.015 to about 0.02, about 0.015 to about 0.019, about0.015 to about 0.018, about 0.015 to about 0.017, about 0.015 to about0.016, about 0.016 to about 0.2, about 0.016 to about 0.019, about 0.016to about 0.018, about 0.016 to about 0.017, about 0.017 to about 0.02,about 0.017 to about 0.019, about 0.017 to about 0.018, about 0.018 toabout 0.02, about 0.018 to about 0.019, or about 0.019 to about 0.02%w/w of nitrogen. In further aspects, the compositions contain about0.005 to about 0.015% w/w of nitrogen. In other aspects, thecompositions contain about 0.01% w/w of nitrogen.

Methods for Preparing the Metal Powders

The metal compositions as described herein may be utilized to preparemetal powders for use in the processes described below. In someembodiments, the metal powders are prepared by atomizing the metalcompositions described herein. For example, the metal compositions aregas atomized or water atomized to provide metal powders. In certainaspects, the metal compositions are gas atomized. In other aspects, themetal compositions are water atomized.

The metal powders of the disclosure are fine powders, i.e., have lowmean particle sizes. Doing so provides high densities of the metalobject and high surface quality. In some embodiments, the surfacequality of the metal object is about 20% better than a similar objectprepared using laser powder bed fusion. The low mean particle size ofthe metal powder may be measured by the d₁₀, d₅₀, and/or d₉₀ values.

The metal powders may have a d₁₀ particle size of about 1 to about 10p.In some aspects, the compositions have a d₁₀ particle size of about 1,about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9,or about 10p. In other aspects, the metal powders have a d₁₀ particlesize of about 1 to about 10p, about 1 to about 9, about 1 to about 8,about 1 to about 7, about 1 to about 6, about 1 to about 5, about 1 toabout 4, about 1 to about 3, about 1 to about 2, about 2 to about 10,about 2 to about 9, about 2 to about 8, about 2 to about 7, about 2 toabout 6, about 2 to about 5, about 2 to about 4, about 2 to about 3,about 3 to about 10, about 3 to about 9, about 3 to about 8, about 3 toabout 7, about 3 to about 6, about 3 to about 5, about 3 to about 4,about 4 to about 10, about 4 to about 9, about 4 to about 8, about 4 toabout 7, about 4 to about 6, about 4 to about 5, about 5 to about 10,about 5 to about 9, about 5 to about 8, about 5 to about 7, about 5 toabout 6, about 6 to about 10, about 6 to about 9, about 6 to about 8,about 6 to about 7, about 7 to about 10, about 7 to about 9, about 7 toabout 8, about 8 to about 10, about 8 to about 9, or about 9 to about10μ.

The metal powders, alternatively or in addition to the d₁₀ particlesize, have a d₅₀ particle size of about 10 to about 20μ. In certainaspects, the metal powders have a d₅₀ particle size of about 10, about11, about 12, about 13, about 14, about 15, about 16, about 17, about18, about 19, or about 20μ. In other aspects, the compositions have ad₅₀ particle size of about 10 to about 19, about 10 to about 18, about10 to about 17, about 10 to about 16, about 10 to about 15, about 10 toabout 14, about 10 to about 13, about 10 to about 12, about 10 to about11, about 11 to about 20, about 11 to about 19, about 11 to about 18,about 11 to about 17, about 11 to about 16, about 11 to about 15, about11 to about 14, about 11 to about 13, about 11 to about 12, about 12 toabout 20, about 12 to about 19, about 12 to about 18, about 12 to about17, about 12 to about 16, about 12 to about 15, about 12 to about 14,about 12 to about 13, about 13 to about 20, about 13 to about 19, about13 to about 18, about 13 to about 17, about 13 to about 16, about 13 toabout 15, about 13 to about 14, about 14 to about 20, about 14 to about19, about 14 to about 18, about 14 to about 17, about 14 to about 16,about 14 to about 15, about 15 to about 20, about 15 to about 19, about15 to about 18, about 15 to about 17, about 15 to about 16, about 16 toabout 20, about 16 to about 19, about 16 to about 18, about 16 to about17, about 17 to about 20, about 17 to about 19, about 17 to about 18,about 18 to about 20, about 18 to about 19, or about 19 to about 20μ.

The metal powders, alternatively or in addition to the d₁₀ and/or d₅₀particle size, have a d₉₀ particle size of about 20 to about 30μ. Incertain aspects, the metal powders have a d₅₀ particle size of about 20,about 21, about 22, about 23, about 24, about 25, about 26, about 27,about 28, about 29, or about 30μ. In other aspects, the compositionshave a d₅₀ particle size of about 20 to about 29, about 20 to about 28,about 20 to about 27, about 20 to about 26, about 20 to about 25, about20 to about 24, about 20 to about 23, about 20 to about 22, about 20 toabout 21, about 21 to about 30, about 21 to about 29, about 21 to about28, about 21 to about 27, about 21 to about 26, about 21 to about 25,about 21 to about 24, about 21 to about 23, about 21 to about 22, about22 to about 30, about 22 to about 29, about 22 to about 28, about 22 toabout 27, about 22 to about 26, about 22 to about 25, about 22 to about24, about 22 to about 23, about 23 to about 30, about 23 to about 29,about 23 to about 28, about 23 to about 27, about 23 to about 26, about23 to about 25, about 23 to about 24, about 24 to about 30, about 24 toabout 29, about 24 to about 28, about 24 to about 27, about 24 to about26, about 24 to about 25, about 25 to about 30, about 25 to about 29,about 25 to about 28, about 25 to about 27, about 25 to about 26, about26 to about 30, about 26 to about 29, about 26 to about 28, about 26 toabout 27, about 27 to about 30, about 27 to about 29, about 27 to about28, about 28 to about 30, about 28 to about 29, or about 29 to about30μ.

The compositions described herein may also be combined with excipientsthat are useful in preparing the metal objects (e.g., green, sintered,and/or annealed). In some embodiments, the excipient is a lubricant or abinder. Lubricants and binding agents that can be used as describedherein are those commonly employed by the powder metallurgy industry.See, e.g., the lubricants described in U.S. Pat. Nos. 4,834,800;4,483,905; 5,298,055; 5,368,630; 5,498,276; 5,330,792; 6,602,315;5,290,336, the disclosures of which are each hereby incorporated byreference in their entireties. In other embodiments, the excipient isgraphite, stearates (such as zinc stearate, lithium stearate, manganesestearate, and calcium stearate), zinc phosphate, boric acid, aceticacid, phosphoric acid, citric acid. amide lubricants (such as ethylenebis-stearamides), polysilazanes, polyureasilazanes,polythioureasilazanes, polycarbosilanes, polysilanes, polysiloxanes,polyborosilazanes, polyaminosilazanes, polyaminoboranes, polyalazanes,polyborazanes, polyphosphazenes, polyphosphinoboranes), polyglycols(such as polyethylene glycol or polypropylene glycol), glycerin,polyvinyl alcohol, homopolymers or copolymers of vinyl acetate,cellulosic ester or ether resins, methacrylate polymers or copolymers,alkyl resins, polyurethane resins, polyester resins, dibasic organicacids (such as azelaic acid), polyethers (liquid or solid), acrylicresins, cellulose ester resins, hydroxy alkylcellulose resins,thermoplastic phenolic resins, polyvinyl pyrrolidone, polyethyleneoxide, low melting, solid polymers or waxes (such as a polymer or waxhaving a softening temperature of below 200° C., e.g., polyesters,polyethylenes, epoxies, urethanes, paraffins, ethylene bis-stearamides,or cotton seed waxes) including paraffin waxes, polyolefins,hydrogenated vegetable oils that are C₁₄₋₂₄ alkyl moiety triglyceridesand derivatives thereof, including hydrogenated derivatives (such ascottonseed oil, soybean oil, jojoba oil, or blends thereof), polyvinylacetate, polyethylene, cellulose ester, or polyvinylpyrrolidone. Incertain embodiments, the excipient is polyethylene, ethylenebis-stearamide, a paraffin wax, or polyvinyl acetate, or a combinationthereof.

Within the scope of the disclosure, the components of the metallurgicalpowder compositions can be added together, combined, and/or bonded inany order.

Methods of Using the Metal Compositions/Powders

The compositions and powders described herein are useful in a variety ofapplications. In some embodiments, the disclosure provides methods ofpreparing metal objects using these compositions and powders. Thedesired shape and type of the metal object may be determined by oneskilled in the art. In certain embodiments, the metal object is abillet, bar, rod, wire, strip, plate, or sheet. In some embodiments, themetal object is an automotive part. In other embodiments, the metalobject is sheet material for an automotive part. In further embodiments,the metal object is sheet material for body automotive parts. In yetother embodiments, the metal object is sheet material for chassisautomotive parts.

The methods include subjecting the metal compositions or powders tometal binder jetting. One of skill in the art would understand the stepsperformed in metal binder jetting.

In summary, metal binder jetting includes depositing the composition orpowder onto a substrate in layers. The substrate does not form part ofthe desired metal object product, but instead is a medium designed tosupport the final metal object. One of skill in the art would be able todetermine the type of substrate and number of layers desired to producethe desired metal object. In some embodiments, there are two or morelayers of the metal composition or powder.

Each layer of the metal composition or powder are held or bound togetherusing a liquid binding agent. In some embodiments, the liquid bindingagent is a polymer. In other embodiments, the liquid binding agent is apolymeric glue. One skilled in the art would be able to select asuitable polymeric glue depending on the metal object to be prepared. Insome aspects, the polymeric glue is polyethylene, ethylenebis-stearamide, or other waxes, among others. The liquid binding agentmay be applied to each layer of the metal powder using a print head. Oneskilled in the art would be able to select a suitable print head,depending on factors such as the desired metal object, metal compositionor powder, among others. The liquid binding agent is applied at athickness as needed by the desired metal object. In some embodiment, thebinding agent is applied at a thickness of about 1 to about 100 microns.In further embodiments, the binding agent is applied at a thickness ofabout 1, about 5, about 10, about 20, about 30, about 40, about 50,about 60, about 70, about 80, about 90, or about 100 microns. In stillother embodiments, the binding about is applied at a thickness of about1 to about 90, about 1 to about 80, about 1 to about 70, about 1 toabout 60, about 1 to about 50, about 1 to about 40, about 1 to about 30,about 1 to about 20, about 1 to about 10, about 10 to about 100, about10 to about 90, about 10 to about 80, about 10 to about 70, about 10 toabout 60, about 10 to about 50, about 10 to about 40, about 10 to about30, about 10 to about 20, about 20 to about 100, about 20 to about 90,about 20 to about 80, about 20 to about 70, about 20 to about 60, about20 to about 50, about 20 to about 40, about 20 to about 30, about 40 toabout 100, about 30 to about 90, about 30 to about 80, about 30 to about70, about 30 to about 60, about 30 to about 50, about 30 to about 40,about 40 to about 100, about 40 to about 90, about 40 to about 80, about40 to about 70, about 40 to about 60, about 40 to about 50, about 50 toabout 100, about 50 to about 90, about 50 to about 80, about 50 to about70, about 50 to about 60, about 60 to about 100, about 60 to about 90,about 60 to about 80, about 60 to about 70, about 70 to about 100, about70 to about 90, about 70 to about 80, about 80 to about 100, about 80 toabout 90, or about 90 to about 100 microns. In yet further embodiments,the binding agent is applied at a thickness of about 50 microns.

Once the metal object is prepared using the metal binder jetting, themetal object is sintered. Doing so provides the desired shape and/ordensity of the metal object. One of skill in the art would be able todetermine suitable sintering conditions, including temperatures, amongothers. In some embodiments, the metal object is sintered at atemperature that provides a crystal structure of the metal object thatis body centered cubic (BCC) ferrite. In other embodiments, the metalobject is sintered at a temperature that provides a crystal structure ofthe metal object that is face centered cubic austenite (FCC). In furtherembodiments, the metal object is sintered at a temperature that providesa crystal structure of the metal object that is BCC and FCC. In yetother embodiments, the sintered metal object comprises an about 1:1ratio of BCC to face centered cubic austenite (FCC). In still furtherembodiments, the metal object comprises about 10 to about 50% w/w, basedon the weight of the metal object, of BCC. In certain embodiments, themetal object comprises about 10, about 20, about 30, about 40, or about50% w/w, based on the weight of the metal object, of BCC. In furtheraspects, the metal object comprise about 10 to about 40, about 10 toabout 30, about 10 to about 20, about 20 to about 50, about 20 to about40, about 20 to about 30, about 30 to about 50, about 30 to about 40, orabout 40 to about 50% w/w, based on the weight of the metal object, ofBCC. In other embodiments, the metal object comprises about 10% to about50% w/w, based on the weight of the metal object, of FCC. In certainembodiments, the metal object comprises about 10, about 20, about 30,about 40, or about 50% w/w, based on the weight of the metal object, ofVCC. In further aspects, the metal object comprise about 10 to about 40,about 10 to about 30, about 10 to about 20, about 20 to about 50, about20 to about 40, about 20 to about 30, about 30 to about 50, about 30 toabout 40, or about 40 to about 50% w/w, based on the weight of the metalobject, of FCC. In still further embodiments, the sintering temperatureis about 700 to about 1500° C. In other embodiments, the sinteringtemperature is about 700, about 750, about 800, about 850, about 900,about 950, about 1000, about 1050, about 1100, about 1150, about 1200,1250, about 1300, about 1350, about 1400, 1450, or about 1500° C. Infurther embodiments, the sintering temperature is about 700 to about1400, about 700 to about 1300, about 700 to about 1200, about 700 toabout 1100, about 700 to about 1000, about 700 to about 900, about 700to about 800, about 800 to about 1500, about 800 to about 1400, about800 to about 1300, about 800 to about 1200, about 800 to about 1100,about 800 to about 1000, about 800 to about 900, about 900 to about1500, about 900 to about 1400, about 900 to about 1300, about 900 toabout 1200, about 900 to about 1100, about 900 to about 1000, about 1000to about 1500, about 1000 to about 1400, about 1000 to about 1300, about1000 to about 1200, about 1000 to about 1100, about 1100 to about 1500,about 1100 to about 1400, about 1100 to about 1300, about 1100 to about1200, about 1200 to about 1500, about 1200 to about 1400, about 1200 toabout 1300, about 1300 to about 1500, about 1300 to about 1400, or about1400 to about 1500° C. In yet other embodiments, the sinteringtemperature is about 1200 to about 1380° C.

After sintering, the sintered metal object has a high density. In someembodiments, the density of the sintered metal object is at least about7.2 g/cm³. In other embodiments, the density of the sintered metalobject is about 7.2 to about 7.8. In further embodiments, the density ofthe sintered metal object is about 7.2, about 7.3, about 7.4, about 7.5,about 7.6, about 7.7, or about 7.8 g/cm³. In yet other embodiments, thedensity of the sintered metal object is about 7.2 to about 7.7, k about7.2 to about 7.6, about 7.2 to about 7.5, about 7.2 to about 7.4, about7.2 to about 7.3, about 7.3 to about 7.8, about 7.3 to about 7.7, about7.3 to about 7.6, about 7.3 to about 7.5, about 7.3 to about 7.4, about7.4 to about 7.8, about 7.4 to about 7.7, about 7.4 to about 7.6, about7.4 to about 7.5, about 7.5 to about 7.8, about 7.5 to about 7.7, about7.5 to about 7.6, about 7.6 to about 7.8, about 7.6 to about 7.7, orabout 7.7 to about 7.8 g/cm³.

The sintered metal object may then be subjected to additional stepsincluding, without limitation, annealing. One of the advantages of themetal compositions or powders of the disclosure is their ability toproduce a metal object that has a dual-phase. Thus, the metal object canbe intercritically annealed at temperatures which vary the level ofaustenite and ferrite. Therefore, heat treatments can be developed toproduce a range of properties with the same alloy. For example, if amaterial with a higher strength is desired, an intercritical annealtemperature at which a higher level of austenite exists can be designedand then a cooling rate can be utilized so that a higher level ofmartensite/bainite is produced, resulting in higher strengths. Inanother example, if a more ductile material is desired, theintercritical annealing temperature is utilized to provide a higherlevel of ferrite, thereby providing a metal object with lower strengthbut higher elongation. In a further example, if steel having an optimumlevel of strength and ductility is desired, the cooling rate isadjusted. In doing so, the cooling rate permits and appropriatemicrostructure to form. It is an advantage of the disclosure that themetal powder for use metal binder jetting can be prepared to meet arange of properties.

In order to provide desirable mechanical properties, the metal objectsprepared herein have optimized ultimate tensile strength, ductility, ora combination thereof. This can be accomplished being adjusting thebainite amounts, martensite amounts, or a combination thereof. Incertain embodiments, the amount of bainite in the metal object is about20 to about 30% w/w, based on the weight of the metal object. In otherembodiments, the amount of bainite in the metal object is about 20,about 21, about 22, about 23, about 24, about 25, about 26, about 27,about 28, about 29, about or about 30% w/w, based on the weight to themetal object. In further embodiments, the amount of bainite, martensite,or a combination thereof in the metal object is about 20 to about 29,about 20 about 28, about 20 to about 27, about 20 to about 26, about 20to about 25, about 20 to about 24, about 20 to about 23, about 20 toabout 22, about 20 to about 21, about 21 to about 30, about 21 to about29, about 21 to about 28, about 21 to about 27, about 21 to about 26,about 21 to about 25, about 21 to about 24, about 21 to about 23, about21 to about 22, about 22 to about 30, about 22 to about 29, about 22 toabout 28, about 22 to about 27, about 22 to about 26, about 22 to about25, about 22 to about 24, about 22 to about 23, about 23 to about 30,about 23 to about 29, about 23 to about 28, about 23 to about 27, about23 to about 26, about 23 to about 25, about 23 to about 24, about 24 toabout 30, about 24 to about 29, about 24 to about 28, about 24 to about27, about 24 to about 26, about 24 to about 25, about 25 to about 30,about 25 to about 29, about 25 to about 28, about 25 to about 27, about25 to about 26, about 26 to about 30, about 26 to about 29, about 26 toabout 28, about 26 to about 27, about 27 to about 30, about 27 to about29, about 27 to about 28, about 28 to about 30, about 28 to about 29, orabout 29 to about 30% w/w, based on the weight of the metal object.

One of skill in the art would be able to determine suitable annealingconditions, including temperatures, among others. In still furtherembodiments, the intercritical annealing temperature is about 600 toabout 1000° C. In other embodiments, the intercritical annealingtemperature is about 600, about 650, about 700, about 750, about 800,about 850, about 900, about 950, or about 1000° C. In furtherembodiments, the intercritical annealing temperature is about 600 toabout 1000, about 600 to about 900, about 600 to about 800, about 600 toabout 700, about 650 to about 1000, about 650 to about 900, about 650 toabout 800, about 650 to about 700, about 700 to about 1000, about 700 toabout 900, about 700 to about 800, about 750 to about 1000, about 750 toabout 900, about 750 to about 800, about 800 to about 1000, about 800 toabout 900, about 850 to about 1000, about 850 to about 900, about 900 toabout 1000, or about 950 to about 1000° C.

Aspects

Aspect 1. A composition comprising iron and:

-   -   about 0.01 to about 0.4% w/w of manganese;    -   about 1.3 to about 1.9% w/w of chromium;    -   about 0.1% w/w or less of nickel;    -   about 1.2 to about 1.7% w/w of molybdenum;    -   about 0.01 to about 0.4% w/w of niobium;    -   about 0.01 to about 0.4% w/w of vanadium;    -   about 1.5 to about 2% w/w of silicon; and    -   about 0.01 to about 0.20% w/w of carbon.

Aspect 2. The composition of claim 1, comprising 0% w/w of nickel.

Aspect 3. The composition of claim 1, comprising about 0.04 to about0.1%, preferably about 0.05 to about 0.07%, or preferably about 0.05%,or preferably about 0.1% w/w of nickel.

Aspect 4. The composition of any one of the preceding claims, comprisingabout 0.1 to about 0.3%, preferably about 0.15 to about 0.25%, orpreferably about 0.2% w/w of manganese.

Aspect 5. The composition of any one of the preceding claims, comprisingabout 1.4 to about 1.8%, preferably about 1.5 to about 1.7%, orpreferably 1.55 to about 1.65%, or preferably about 1.6% w/w ofchromium.

Aspect 6. The composition of any one of the preceding claims, comprisingabout 1.3 to about 1.6%, preferably about 1.4 to about 1.5, orpreferably about 1.45% w, or preferably about 1.5% w/w of molybdenum.

Aspect 7. The composition of any one of the preceding claims, comprisingabout 0.1 to about 0.3, preferably about 0.15 to about 0.2, orpreferably about 0.18% w/w of niobium.

Aspect 8. The composition of any one of the preceding claims, comprisingabout 0.1 to about 0.3, preferably about 0.15 to about 0.2, orpreferably about 0.18% w/w of vanadium.

Aspect 9. The composition of any one of the preceding claims, comprisingabout 1.5 to about 1.8%, preferably about 1.5 to about 1.7%, orpreferably about 1.6 to about 1.7%, or preferably about 1.6% w/w ofsilicon.

Aspect 10. The composition of any one of the preceding claims,comprising about 0.05 to about 0.14%, preferably about 0.1 to about0.14%, or preferably about 0.14% w/w of carbon.

Aspect 11. The composition of any one of the preceding claims, furthercomprising sulfur.

Aspect 12. The composition of claim 11, comprising about 0.001 to about0.015%, preferably about 0.005 to about 0.01%, or preferably about 0.006to about 0.008%, or preferably about 0.007% w/w of sulfur.

Aspect 13. The composition any one of the preceding claims, furthercomprising oxygen.

Aspect 14. The composition of claim 13, comprising about 0.01 to about0.1%, preferably about 0.04 to about 0.08%, or preferably about 0.05 toabout 0.07%, or preferably about 0.06% w/w of sulfur.

Aspect 15. The composition of any one of the preceding claims, furthercomprising nitrogen.

Aspect 16. The composition of claim 15, comprising about 0.01 to about0.02%, preferably about 0.015 to about 0.015%, or preferably about 0.01%w/w of nitrogen.

Aspect 17. The composition of any one of the preceding claims, that is ametal powder.

Aspect 18. The composition of any one of the preceding claims, having ad₁₀ particle size of about 1 to about 10μ, a d₅₀ particle size of about10 to about 20μ, or a d₉₀ particle size of about 20 to about 30μ, orcombinations thereof.

Aspect 19. A method of preparing a metal powder, comprising atomizingthe composition of any one of the preceding claims.

Aspect 20. The method of claim 18, wherein the atomizing is gas or wateratomizing.

Aspect 21. A metal powder prepared according to the method of claim 18or 19.

Aspect 22. The metal powder of claim 10, having a d₁₀ particle size ofabout 1 to about 10μ, a d₅₀ particle size of about 10 to about 20μ, or ad₉₀ particle size of about 20 to about 30μ, or combinations thereof.

Aspect 23. A method of preparing a metal object, comprising subjectingthe metal powder of claim 18 or 19 to metal binder jetting.

Aspect 24. The method of claim 20, comprising depositing two or morelayers comprising the metal working composition of claim 1 onto asubstrate.

Aspect 25. The method of claim 21, wherein the layers are bound togetherusing a liquid binding agent.

Aspect 26. The method of any one of claims 20 to 22, further comprisingsintering the metal object.

Aspect 27. The method of claim 23, wherein the metal object is sinteredat a temperature region at which the crystal structure of the alloy isbody centered cubic (BCC) ferrite.

Aspect 28. The method of claim 23 or 24, wherein the sintered metalobject comprises an about 1:1 ratio of BCC to face centered cubicaustenite (FCC).

Aspect 29. The method of any one of claims 23 to 25, wherein thesintering temperature is about 700 to about 1500° C.

Aspect 30. The method of any one of claims 23 to 26, wherein the densityof the sintered metal object is at least about 7 g/cm³.

Aspect 31. The method of any one of claims 23 to 27, wherein thesintered metal object is annealed.

Aspect 32. The method of claim 28, wherein the intercritical annealingtemperature is about 600 to about 1000° C.

Aspect 33. A metal object prepared according to any one of claims 23-32.

The following examples are provided to illusrate 4 some of the conceptsdescribed within this disclosure. While each Example is considered toprovide specific individual embodiments of compositions, methods ofpreparation and use, none of the Examples should be considered to limitthe more general embodiments described herein.

Example 1: Reagents and Procedures

Powders are gas atomized with nitrogen as the atomizing gas. Chemicalanalysis and powder properties are listed in Tables 1A and 1B. Particlesize of each alloy is typical for use in metal binder jetting.

TABLE 1A Powder Properties of gas atomized alloys. Material Mn Cr Ni MoNb V Si FSLA Powder 0.20 1.60 0.06 1.45 0.18 0.18 1.64 DP 600 Powder1.62 0.20 0.10 0.05 NA NA 0.20

TABLE 1B Powder Properties of gas atomized alloys. Apparent Tap DensityDensity C S O N d₁₀ d₅₀ d₉₀ Material (g/cm³) (g/cm³) (w/w) (w/w) (w/w)(w/w) (μ) (μ) (μ) FSLA Powder 3.2 4.9 0.14 0.007 0.06 0.01 5.7 14.0 24.4DP 600 Powder 3.3 4.5 0.14 0.014 0.12 0.01 5.7 15.1 26.8

All test samples are printed on an HP Multi Jet Fusion Printer, with awater-based binder available in the art at a 50-micron layer thickness.

Test pieces are sintered at DSH Technologies utilizing MIM3045T furnacesfrom Elnik Systems. These furnaces combine thermal debind and the sinterprocess all in one furnace. The equipment has a maximum temperature of1600° C. with partial pressure or vacuum control. The furnace is an allmetal process zone with atmosphere capabilities of pure hydrogen,nitrogen, argon, or vacuum environments. Test pieces are sintered in ahigh temperature Elnik MIM at 1380° C. for 30 min in an atmosphere of 95v/w nitrogen/5 v/w hydrogen.

For continuous heat treatment, a high temperature Abbott continuous-beltfurnace is used at indicated temperatures for 30 min in an atmosphere of95 v/w nitrogen/5 v/w hydrogen.

Prior to mechanical testing, green and sintered densities, dimensionalchange (DC), and apparent hardness are determined on the tensile andtransverse rupture (TR) samples. Five tensile specimens and five TRspecimens are evaluated for each composition. The densities of the greenand sintered steels are determined in accordance with MPIF Standard 42.Tensile testing followed MPIF Standard 10 and apparent hardnessmeasurements are made on the tensile and TR specimens, in accordancewith MPIF Standard 43.

Porosity measurements are made on metallographically preparedcross-sections removed from entire test parts. A Clemex automated imageanalysis system is used to measure and map the porosity on as-preparedsurfaces using a predetermined gray level to separate the dark voidspace and from the highly light reflective metallic regions. The porecontent also is estimated in both the sample volume and in localizedregions.

Specimens for microstructural characterization are prepared usingstandard metallographic procedures. Subsequently, they are examined byoptical microscopy in the polished and etched (2 v/o nital/4 w/o picral)conditions.

In addition, the microstructure is revealed, and color used to separatethe transformation products with a two-step, etch/stain, process. First,the microstructure is defined with a light pre-etch by immersing thesample in Vilella's reagent (5 ml HCl+1 g picric acid+100 ml ethylalcohol), rinsing with warm water, and drying with filtered compressedair. In the second step, the pre-etched sample is immersed in a freshlyprepared solution of 10 g sodium metabisulphite (Na₂S₂O₅) in 100 mldeionized or distilled water, rinsed with warm water and alcohol, thendried with filtered compressed air.

Example 2: Alloy Design

For metal binder jetting, the as-built density from the printer itselfis typically not much higher than the apparent density of the powder(˜60%). Despite the fact that many of the additive manufacturing machinemanufacturers are now designing the roller system, which spreads thepowder, to exert some force on the powder bed to densify the built part,the manner in which the powder fills the print bed dictates the finalpart density after printing. FIG. 1 highlights that due to the initiallow as built density parts printed from metal binder jetting, higherenergy input is needed to achieve densities typical of conventionalpowder metallurgy or MIM processes. FIG. 1 shows that the as builtdensity for 316 L specimens produced by metal binder jetting ranges from3.8-4.6 g/cm³. As an example, typical densities prior to sintering for316 L when processed by MIM are around 5.5 g/cm³ and for conventionalpowder metallurgy typically 6.7 g/cm³ (when compacted at 690 MPa).Therefore, longer sintering times and higher sintering temperatures areneeded to achieve the same final densities in metal binder jetting. Evenat the higher as built densities and utilizing a very fine powder size(8-12 microns), when the material is sintered at 1260° C. in 100 vol %hydrogen, only densities approaching 7.0 g/cm³ are realized.

In this example, the metal powders of the disclosure are shown toenhance the sinterability of the metal binder jetting part; it sintersin a temperature region at which the crystal structure of the alloy isbody centered cubic (BCC) ferrite rather than face centered cubicaustenite (FCC). Thus, the metal powder balances the constituents toachieve roughly a 50/50 mixture of austenite and ferrite at thesintering temperature (1380° C.).

The metal powders are prepared using the amounts of carbon, silicon,manganese, molybdenum, nickel and chromium as shown in Table 2.

TABLE 2 Nominal chemical composition of wrought DP600 alloy, DP600atomized powder and new additive manufacturing grade designated as FSLAC Si Mn Mo Ni Cr Material^(c) (w/w) (w/w) (w/w) (w/w) (w/w) (w/w) DP600Wrought^(a) 0.14 (max) 1.50 (max) 2.00 (max) 1.0 (max) DP600 Powder^(b)0.12 0.05 1.62 0.05 0.09 0.17 Disclosure Metal Powder 0.14 (max) 1.600.17 1.50 0.10 1.60 ^(a)= DP600 product in the form of a solid; ^(b)=DP600 product in the form of a powder; ^(c)= these materials alsocontain iron.

At temperatures above 1120° C., which are commonly used for sintering,the metal powder of the disclosure forms a high percentage of ferrite.FIG. 2 compares the phase diagrams for the metal powder of thedisclosure and a conventional DP600 wrought alloy. The DP600 wroughtalloy is a dual phase wrought alloy consisting of roughly 20-25% vol %martensite in a ferrite matrix which is normally produced by controlledrolling combined with secondary heat treatment. The DP600 wrought alloyis commonly used in the body structure of the car.

In addition, the conventional composition of dual phase steels, whichconsists primarily of low carbon levels and up to 2% w/w manganese, isnot conducive to the sintering process. In the metal powder of thedisclosure, the temperature range, over which the ferrite phase exists,is very broad and corresponds to typical sintering temperatures (700 to1400° C.). A comparison of the phases existing in a standard dual phasesteel (DP600) over the same temperature range, indicate only austeniteexists in the temperature window for sintering.

Another significant difference between the wrought DP600 compositionfrom the art and the metal powder of the disclosure is the presenceniobium and vanadium.

Example 3: Density Considerations

In general, the metal binder jetting process cannot achieve full densityin comparison to the wrought grade, unless special techniques such asliquid phase sintering or hot isostatically pressing (after initialsintering) are utilized. For this reason, high temperatures and longtimes at temperature are generally employed for sintering of the greenparts.

To maximize the density under these conditions, the metal powder of thedisclosure of Example 2 was tested. In summary, the metal powder ofExample 2 was subjected to metal binder jetting to provide the greenmetal object, and the metal object was sintered. The densities of themetal powder, the green metal object, and the sintered metal object wasobtained. See, Table 3 which shows the density of metal objects producedwith the DP600 wrought iron metal powder and the metal powder of thedisclosure in atomized (apparent density), built (green density) andsintered density (final density). The change in density occurred duringsintering. Since both materials are subjected to the same sinteringcycle, the metal powder of the disclosure exhibits better sinterabilitythan the DP600 product. At the sintering temperatures utilized, theDP600 product is in austenite form (100%) while the metal powder of thedisclosure has a microstructure of approximately 50 vol % ferrite and 50vol % austenite. Further, the density increase for the metal powder ofthe disclosure is quite dramatic approaching 1 g/cm³.

TABLE 3 Density of DP600 and FSLA at various stages of the processApparent As Build Sintered Density Density Density Material (g/cm³)(g/cm³) (g/cm³) DP600 Powder 4.25 4.13 6.53 Disclosure Metal 4.00 4.647.48 Powder

Example 4: Processing of the Metal Compositions

Intercritical annealing is a processing step in producing dual phasesteels. The intercritical anneal temperature is chosen to control thevolume fractions of the ferrite and austenite (which then transformsduring cooling). In order to ascertain the intercritical annealingtemperature for the metal powder of the disclosure to produce 20-30% ofthe transformation products (e.g., microstructure of either bainite ormartensite prepared by cooling), individual samples of the sinteredmetal object of Example 3 are heated to various temperatures within inthe austenite/ferrite region as shown in the FSLA phase diagram. See,FIG. 2 . Samples are quenched and then microstructural analysis used todetermine the level of ferrite in the microstructure and compared to thepredictions made using a thermodynamic software package (Thermocalc).The results of this experiment are shown in FIG. 3 .

In general, the agreement between the actual measured values and thosepredicted is good. The results indicate that in order to achieve amicrostructure of about 20-30% of bainite/martensite, an intercriticalannealing temperature of about 750 to 950° C. is utilized. Anothercomponent of the intercritical annealing process is the cooling rate.FIG. 4 shows a Continuous Cooling Transformation Diagram (CCT Diagram)for the metal powder of the disclosure. See, Tables 1A and 1B.

The cooling rate achieved utilizing the continuous belt furnace is shownin FIG. 4 in the CCT diagram as the vertical line between the hardnessof 498 and 522. The samples are heated to 843° C. which placed thematerial into the two-phase region of the phase diagram (FIG. 2 ) whichcontained unstable austenite and stable ferrite. The maximum coolingrate of the furnace is utilized, 1.3° C./sec (as indicated by thevertical line between the hardness of 498 and 522). The CCT diagramindicates that the unstable austenite when cooled from 843° C. willtransform to bainite. To form martensite, a cooling rate of 16-20°C./sec should be utilized.

Upon cooling, the CCT curve indicates that the unstable austenite willtransform to bainite at the used cooling rate. The resultingmicrostructure is shown in FIG. 5 . The structure shows that theoriginal unstable austenite has transformed to bainite and the twodifferent forms of ferrite. There is ferrite surrounding thetransformation product (bainite) that due to the change in crystalstructure of the austenite upon cooling gets deformed and dislocationsform within the adjacent ferrite. The dislocations in the ferritegenerally lead to an increase in the work hardening rate and increasethe strength of the ferrite.

A second ferrite that is located away from this transformation andadjacent to the dislocated ferrite that is not stressed also is present.Table 4 shows the percentage of each phase along with themicro-indentation hardness corresponding to each. The ferrite with thedislocated structure has a higher hardness.

TABLE 4 Percentage of phases and corresponding micro-indentationhardness of each phase using a metal powder of the disclosureintercritically annealed at 850° C. and cooled at 1.3° C./sec. % Ferrite% Ferrite % Bainite (Light) (Dark) % of Phase 19.2 34.4 46.4 Micro- 360284 321 indentation (HV50gf) (HV50gf) (HV50gf) Hardness

FIG. 6 shows electron backscattered diffraction (EBSD) results of themicrostructure of the annealed metal powder of the disclosure. As knownin the art, EBSD is a technique utilized to measure the amount of phasesand stresses in the metal object microstructure. These EBSD results showthat ferrite grains next to the transformation products (bainite in thiscase) contain a significant amount of dislocations. These dislocationscontribute to the work-hardening of the alloy and provide a metal objectwith high ultimate tensile strength with continuous yielding and highductility.

The degree of the precipitation strengthening in metal objects dependson the volume fraction, the size, and the type of precipitates, amongothers. FIG. 7 shows examples of precipitates that form in the metalpowder of the disclosure after heat treatment. Examples shown byscanning electron microscopy (SEM) and energy dispersive X-raySpectroscopy (EDS) shows the presence of both individual niobium richcarbides along with networks of molybdenum rich carbides. See, thespectral data in Tables 5 and 6.

TABLE 5 Spectrum Label Spectrum Spectrum Spectrum Spectrum Spectrum 2930 31 32 33 C 8.79 9.15 8.03 10.39 10.03 Si 2.22 2.15 2.20 2.49 2.18 V0.33 0.35 0.29 0.37 0.32 Cr 2.09 1.98 1.86 1.90 1.95 Fe 77.70 78.4280.90 76.30 77.86 Mo 8.87 7.97 6.72 8.56 7.36 Total 100.00 100.00 100.00100.00 100.00

TABLE 6 Spectrum Label Spectrum Spectrum Spectrum Spectrum 34 35 36 37 C15.79 9.45 9.43 5.96 Si 1.84 2.20 2.30 1.43 V 0.30 0.34 0.35 Cr 1.601.97 1.89 1.74 Fe 69.68 78.04 79.34 89.91 Mo 5.03 8.01 6.69 0.96 Total100.00 100.00 100.00 100.00

When the precipitates are located within the grains, they impededislocation motion and therefore increase the strength and hardness ofthe alloy. After sintering, any precipitates located at the grainboundaries pin the grain boundaries and limit grain growth during theintercritical annealing step. This restriction of grain growth alsoimproves the strength of the material.

The typical size of the NbC, VN or TiC in wrought steels is between 2 to100 nanometers. When using the metal powder of the disclosure andsintering conditions of 1380° C. in an atmosphere is 95% nitrogen and 5%hydrogen, NbC, VC and other alloyed carbides are observed. The averagesize of the precipitates is between 0.3 and 0.4 microns (300 to 400nanometers), which contributes to the higher strength of the metalobject. See, FIG. 8 . The precipitates are formed during sintering inthe ferrite phase field. The precipitation strengthening is calculatedusing the following calculation for this coarser particle size and foundto be between 40 and 50 MPa. See, FIG. 10 . This is a significantcontribution of strength by precipitation hardening.

$\sigma_{ppt} = {( \frac{0.538*G*b*f^{1/2}}{X} )*{\ln( \frac{X}{2b} )}}$Variable Utilized Variable X = average precipitates diameter — (μm) f =precipitates area fraction (%) — d = average grain size (mm) — σ₀ =lattice friction stress (MPa) 80 (MPa) k_(y) = Hall Petch factor (MPa *mm^(1/2)) 24 b = Burger's vector (μm) 0.00025 G = Matrix shear modulus(MPa) 83000

Example 6: Properties

In this example, it is shown that the metal powder of the disclosure ofExample 2, once sintered and heat treated, together with metal binderjetting provides a metal object alloy that achieves a mechanicalproperty level of a conventional DP600 wrought alloy, i.e., an ultimatetensile strength of at least about 600 MPa.

To evaluate the level of the mechanical properties and consistency ofthe binder jet printing along with the sintering and heat treatment,separate print runs are processed with the same parameters for each stepbut at different times. The properties of these individual runs areshown in Table 7 along with a typical wrought specification. Theultimate tensile strength and yield strength of the metal powder of thedisclosure was similar to the wrought DP600 while the elongationpercentage is somewhat lower than the minimum. Based on the porositydata, the metal powder of the disclosure reached only 97-98% of thetheoretical density.

TABLE 7 Mechanical Properties of various print runs of the metal binderjetting FSLA alloy UTS 0.2% YS Elongation Hardness As Built (MPa) (MPa)(%) (HRA) DP500 580-670 330-470 24 (min) — (Salzgitter) Run 1 684 39719.9 51 Run 2 691 383 19.4 49 Run 3 673 387 20.3 50 Run 4 692 404 19.952 Run 5 696 404 19.2 52 Run 6 683 396 19.4 51 Average 687 395 19.7 51

Example 7: Annealing Temperature Variations

As discussed previously, one of the advantages of a dual-phase material,is that it can be intercritically annealed at temperatures which varythe level of austenite and ferrite. Therefore, heat treatments can bedeveloped to produce a range of properties with the same alloy. See FIG.3 .

The metal powders discussed herein may be utilized to meet a range ofproperties of the produced metal object. For example, for metal binderjetting materials, developing print parameters and sintering profilescan be time consuming and influenced by the composition of the metalpowder. Having one metal powder that covers a range of properties leadsto faster material development and industrialization. Table 8 shows arange of properties of the FSLA material achieved with the same printingand sintering parameters, but different intercritical annealtemperatures and cooling rates.

TABLE 8 Mechanical Properties of metal binder jetting FSLA alloyutilizing various Intercritical Annealing Temperatures UTS 0.2% YSElongation Hardness As Built (MPa) (MPa) (%) (HRA) As Built 712 393 10.155 IA 650° C. 792 473 9.6 55 IA 760° C. 734 459 14.0 56 IA 843° C. 708408 19.3 53

Table 8 shows that a the FSLA alloy exhibits a range of UTS strengthsfrom 700-800 MPa (an increase in 15%) with just a change in theintercritical anneal temperature. As the strength increases theductility decreases.

While the expectation for all additive manufacturing processes is high,metal binder jetting suffers from the fact that without specialtechniques, such as liquid phase sintering or hot isostatic pressing,full density cannot be achieved. FIG. 8 shows how the metal powder ofthe disclosure with various heat treatments and carbon levels compareswith typical dual phase steels. As previously mentioned, due to theporosity still remaining in the metal powder of the disclosure (about2.5%), the ductility still is lower than the conventional dual phasesteels (about 20% versus minimum of 24%).

The contents of all references, patent applications, patents, andpublished patent applications, as well as the Figures, cited throughoutthis application are hereby incorporated by reference.

Those skilled in the art will recognize, or be able to ascertain usingno more than routine experimentation, many equivalents to the specificembodiments of the disclosure described herein. such equivalents areintended to be encompassed by the following claims.

1. A composition comprising iron and: about 0.01 to about 0.4% w/w ofmanganese; about 1.3 to about 1.9% w/w of chromium; about 0.1% w/w orless of nickel; about 1.2 to about 1.7% w/w of molybdenum; about 0.01 toabout 0.4% w/w of niobium; about 0.01 to about 0.4% w/w of vanadium;about 1.5 to about 2% w/w of silicon; and about 0.01 to about 0.20% w/wof carbon.
 2. The composition of claim 1, comprising 0% w/w of nickel.3. The composition of claim 1, comprising about 0.04 to about 0.1% w/wof nickel.
 4. The composition of claim 1, comprising about 0.1 to about0.3% w/w of manganese.
 5. The composition of claim 1, comprising about1.4 to about 1.8% w/w of chromium.
 6. The composition of claim 1,comprising about 1.3 to about 1.6% w/w of molybdenum.
 7. The compositionof claim 1, comprising about 0.1 to about 0.3 w/w of niobium.
 8. Thecomposition of claim 1, comprising about 0.1 to about 0.3 w/w ofvanadium.
 9. The composition of claim 1, comprising about 1.5 to about1.8% w/w of silicon.
 10. The composition of claim 1, comprising about0.05 to about 0.14% w/w of carbon.
 11. The composition of claim 1,further comprising sulfur.
 12. The composition of claim 11, comprisingabout 0.001 to about 0.015% w/w of sulfur.
 13. The composition of claim1, further comprising oxygen.
 14. The composition of claim 13,comprising about 0.01 to about 0.1% w/w of oxygen.
 15. The compositionof claim 1, further comprising nitrogen.
 16. The composition of claim15, comprising about 0.01 to about 0.02% w/w of nitrogen.
 17. Thecomposition of claim 1, that is a metal powder.
 18. The composition ofclaim 1, having a d₁₀ particle size of about 1 to about 10μ, a d₅₀particle size of about 10 to about 20μ, or a d₉₀ particle size of about20 to about 30μ, or combinations thereof.
 19. A method of preparing ametal powder, comprising atomizing the composition of claim
 1. 20. Themethod of claim 19, wherein the atomizing is gas or water atomizing. 21.A metal powder prepared according to the method of claim
 19. 22. Themetal powder of claim 21, having a d₁₀ particle size of about 1 to about10μ, a d₅₀ particle size of about 10 to about 20μ, or a d₉₀ particlesize of about 20 to about 30μ, or combinations thereof.
 23. A method ofpreparing a metal object, comprising subjecting the metal powder ofclaim 19 to metal binder jetting.
 24. The method of claim 23, comprisingdepositing two or more layers comprising the metal working compositionof claim 1 onto a substrate.
 25. The method of claim 24, wherein thelayers are bound together using a liquid binding agent.
 26. The methodof claim 23, further comprising sintering the metal object.
 27. Themethod of claim 26, wherein the metal object is sintered at atemperature region at which the crystal structure of the alloy is bodycentered cubic (BCC) ferrite.
 28. The method of claim 26, wherein thesintered metal object comprises an about 1:1 ratio of BCC to facecentered cubic austenite (FCC).
 29. The method of claim 26, wherein thesintering temperature is about 700 to about 1500° C.
 30. The method ofclaim 26, wherein the density of the sintered metal object is at leastabout 7 g/cm³.
 31. The method of claim 26, wherein the sintered metalobject is annealed.
 32. The method of claim 31, wherein theintercritical annealing temperature is about 600 to about 1000° C.
 33. Ametal object prepared according to the method of claim 23.